Cooling Module with Multiple Parallel Blowers

ABSTRACT

A cooling fan module for motivating air flow through an electronics chassis includes an enclosure having an air inlet through which cooling air flow is motivated by at least two centrifugal blowers disposed within the enclosure. The centrifugal blowers operate in parallel to motivate the cooling air flow along a first direction vector, while the respective axes of rotation of the centrifugal blower impellers are in substantial axial alignment with one another, and parallel to the first direction vector.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. provisional Patent ApplicationSer. No. 61/356,374, filed on Jun. 18, 2010 and entitled “Cooling Modulewith Multiple Parallel Blowers”, the content of which being incorporatedherein in its entirety.

FIELD OF THE INVENTION

The present invention relates to cooling systems generally, and moreparticularly to a cooling fan module for motivating cooling air flowthrough an electronics chassis, wherein the cooling fan module issubstantially more efficient and produces substantially less noise thanconventional cooling fan arrangements, without requiring increasedvolume.

BACKGROUND OF THE INVENTION

This invention relates to a module, commonly referred to as a fan tray,designed to provide cooling flow to an electronics apparatus.Specifically, the module contains a parallel flow arrangement ofcentrifugal blowers. The present arrangement optimizes performance ofthe module by employing high efficiency forward curved centrifugalblowers arranged in a specific relationship axially in line with theprimary air inlet to the module. The module is especially well suitedfor cooling of telecommunication routers and similar high powered,densely populated electronic equipment.

Designers of electronic equipment have become increasingly challenged toprovide high-power devices in relatively small packages. These devicesrequire compact and highly efficient cooling systems. A typical coolingsystem involves moving air across one or more printed circuit cards. Theflow path layout, type of air moving device, and how well it isintegrated into the system, are all key elements in achieving thedesired performance in a small package size with low noise.

One such electronic device is the telecommunications router. The desireto make them more powerful, yet compact in size, leaves little space forcooling system components necessary to address ever-increasing heatloads. Conventional system designs often employ fans that are not wellmatched to the system pressures, or do not move air efficiently withinthe space constraints, and result in unacceptable noise, and relativelylarge power consumption.

Design efforts to date typically use multiple axial fans arranged inparallel in a “tray”, refer to FIGS. 2 a and 2 b. The fans either pushcool air through a chassis or pull warm air out of a chassis. Sometimestwo trays are arranged in series as a push and pull-through system.Relatively high aerodynamic efficiencies can be achieved with this typeof air mover, but unfortunately they require high rotational speeds thattypically result in unacceptable acoustic signatures. Alternatearrangements include “Backward Curved” (BC) centrifugal type blowerspulling air through a chassis, refer to FIGS. 3 a and 3 b. These fanstypically have similar acoustic performance to axial fans, and theyrequire relatively large diffusers to realize acceptable aerodynamicefficiency. Typical packaging constraints don't allow for properdiffusers, resulting in poor system efficiencies, and compromisedacoustics.

In still further conventional arrangements, “Forward Curved” (FC)centrifugal type blowers may be arranged in a module for pulling airthrough a chassis, but are typically arranged with the blower inletsperpendicular to, or otherwise not in axially aligned relationship with,the air inlet to the fan module, refer to FIGS. 4 a and 4 b. Sucharrangements do not provide the desired efficiencies and acoustics ofthe present invention.

SUMMARY OF THE INVENTION

By means of the present invention, electronics applications withhigh-density component populations may be efficiently and effectivelycooled with a low-volume cooling module. The specific arrangement offorward-curved centrifugal blowers of the present invention facilitatesthe creation of a cooling module of low physical volume thatnevertheless generates desired levels of air movement power atsubstantially reduced noise. Electronics chassis manufacturers,therefore, are able to achieve high performance within small-volumepackages.

In one embodiment, a cooling fan module of the present inventionincludes an enclosure having an air inlet through which air flow isdrawn from an associated electronics chassis. At least two centrifugalblowers may be disposed within the enclosure, and in parallel motivatethe air flow along a first direction vector through the air inlet. Eachof the centrifugal blowers include a scroll housing defining an airinlet and an air discharge, a forward-curved impeller having a diameterdimension and defining an axis of rotation, and a motor for rotation ofthe impeller about the axis. The axis of rotation extends through thehousing air inlet and substantially parallel to the first directionvector. The respective axes of rotation of the centrifugal blowerimpellers may be in substantial axial alignment with one another.

In another embodiment, a cooling fan module of the present inventionincludes an enclosure having an air inlet through which air flow isdrawn from an associated electronic chassis, and a first set of aplurality of centrifugal blowers disposed within the enclosure. Thefirst set of centrifugal blowers in parallel motivate air flow along afirst direction vector into the enclosure. Each of the centrifugalblowers of the first set includes a scroll housing defining an air inletand an air discharge, a forward-curved impeller having a diameterdimension and defining an axis of rotation, and a motor for rotation ofthe impeller about the axis. The axis of rotation extends through thehousing air inlet substantially parallel to the first direction vector.The respective axes of rotation of the centrifugal blower impellers maybe in substantial axial alignment with one another. The cooling fanmodule may further include a second set of one or more blowers disposedwithin the enclosure and motivating the air flow along a seconddirection vector into the enclosure, wherein the second direction vectoris substantially perpendicular to the first direction vector.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a is a partial cut away view of a cooling fan module of thepresent invention;

FIG. 1 b is a schematic illustration of the cooling fan module of FIG. 1in combination with an electronics chassis;

FIG. 2 a is a partial cut away view of a cooling fan module of the priorart;

FIG. 2 b is a schematic illustration of cooling fan modules asillustrated in

FIG. 2 a in combination with an electronics chassis;

FIG. 3 a is a partial cut away view of a cooling fan module of the priorart;

FIG. 3 b is a schematic illustration of the cooling fan module of FIG. 3a in combination with an electronics chassis;

FIG. 4 a is a partial cut away view of a cooling fan module of the priorart;

FIG. 4 b is a schematic illustration of the cooling fan module of FIG. 4a in combination with an electronics chassis;

FIG. 5 a is a partial cut away view of a cooling fan module of thepresent invention;

FIG. 5 b is a schematic illustration of the cooling fan module of FIG. 5a in combination with an electronics chassis; and

FIG. 6 is a schematic illustration of a cooling fan module of thepresent invention in combination with an electronics chassis.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The objects and advantages enumerated above together with other objects,features, and advances represented by the present invention will now bepresented in terms of detailed embodiments described with reference tothe attached drawing figures which are intended to be representative ofvarious possible configurations of the invention. Other embodiments andaspects of the invention are recognized as being within the grasp ofthose having ordinary skill in the art.

The present invention addresses the efficiency and noise issues outlinedabove. The preferred embodiment includes an air mover module set up tomotivate air through an electronics chassis, wherein the module employsmultiple forward curved (FC) centrifugal blowers arranged in a parallelflow configuration, and the blower air inlets are arranged axiallyin-line with module primary inlet, refer to FIGS. 1 a & 1 b. Thisarrangement provides high efficiency and low noise in a relatively smallpackaging volume. The present invention uses several features, incombination, to achieve high performance within the constraintsoutlined.

As illustrated in FIGS. 1 a and 1 b, a cooling fan module 10 may bearranged to pull air flow through an electronic chassis 12 to coolelectronics disposed in the chassis 12. Example electronics chassis 12that may contain electronic components in need of the presently proposedcooling include telecommunication routers, servers, and power supplyunits. Cooling fan module 10 includes an enclosure 14 having an airinlet 16 though which air flow (represented by arrows) is drawn fromelectronics chassis 12. In the illustrated embodiment, cooling air flowis motivated through an interior chamber 13 of chassis 12, and through aplenum 15 to reach air inlet 16 of cooling fan module 10. It iscontemplated that module 10 may be secured to or integrally formed withchassis 12 in any suitable manner to achieve cooling air flow motivationthrough inlet 16. Specifically, the arrangements of the presentinvention need not include plenum 15, and may position module 10directly in line with initial air flow direction 17.

Module 10 further includes a plurality of centrifugal blowers 18disposed within enclosure 14 and in parallel motivating the air flowgenerally along a first direction vector 20 through air inlet 16.Centrifugal blowers 18 motivate the air flow in parallel by eachindividually acting upon air flow entering air inlet 16 to thereforedirect air flow along first direction vector 20. In addition,centrifugal blowers 18 motivate the air flow in parallel by receivingair to their respective inlets that is sourced directly from air passingthorough chassis 12, and not as exhaust from an “upstream” blower. Asillustrated in Figure lb, discharge from each centrifugal blower 18exits enclosure 14, and is therefore not fed to a subsequent blower 18.In this manner, centrifugal blowers 18 are considered to motivate theair flow “in parallel.”

Each of centrifugal blowers 18 includes a scroll housing 22 whichdefines an air inlet 24 and an air discharge 26. Centrifugal blowers 18further include a forward-curved impeller 19 having a diameter dimension“x”, and defining an axis of rotation 28 which extends through housingair inlet 24 and substantially parallel to first direction vector 20.The centrifugal blowers 18 each further include a motor 30 for rotationof the respective impellers 19 about axis 28. As illustrated in Figurelb, the respective axes of rotation 28 of the centrifugal blowerimpellers are in substantial axial alignment with one another.

The arrangement described above has been found to provide surprisinglyenhanced aerodynamic efficiency for each blower 18, such that totalpower input to motivate a desired air flow may be reduced. In addition,the surprising efficiency of the proposed arrangement reduces soundemissions, which is also a beneficial operating characteristic of thefan modules of the present invention.

In further description of module 10, enclosure 14 includes first andsecond ends 40, 42 separated by one or more side walls 44. Air inlet 16may be disposed at first end 40 of enclosure 14. In the illustratedembodiment, the air inlets 24 of each of centrifugal blowers 18 may bearranged in enclosure 14 in facing relationship with enclosure air inlet16. In other embodiments, however, one or more of such centrifugalblower air inlets 24 may be facing substantially away from enclosure airinlet 16.

As further illustrated in Figure lb, the respective air discharges 26 ofcentrifugal blowers 18 may be arranged to emit air along a seconddirection vector 50 which is substantially perpendicular to firstdirection vector 20.

For the purposes hereof, the term “axial alignment” is intended to meanthat the respective axes of rotation of the centrifugal blower impellersare arranged in precise axial alignment, or in close substantiallyparallel proximity thereto. The term “axial alignment” may thereforeinclude respective axes of rotation 28 which are substantially parallelto the remaining axes of rotation 28, and are spaced apart by no morethan a dimension equal to diameter dimension “x” of the centrifugalblower impeller 19. An example arrangement of centrifugal blowers whichare in “axial alignment” for the purposes hereof is illustrated in FIG.6. As shown therein, each of the respective axes of rotation 28 a-28 eare within a dimension X₁ that is substantially equal to a diameterdimension “x” of the centrifugal blower impeller.

A further embodiment of the present invention is illustrated in FIGS. 5a and 5 b, wherein a first set of a plurality of centrifugal blowers 60is arranged as described above, and wherein a second set of one or moreblowers 70 may be arranged and positioned to motivate the air flow alonga direction substantially parallel to second direction vector 50, orsubstantially perpendicular to first direction vector 20. Thus, in theembodiment illustrated in FIGS. 5 a and 5 b, module 110 includes firstand second sets of blowers, wherein a first set motivates air flow intomodule 110 substantially along first direction vector 20, while a secondset of blowers 70 motivates air flow into module 110 along seconddirection vector 50. In this embodiment, first set of centrifugalblowers 60 includes a plurality of centrifugal blowers, and second setof blowers 70 includes one or more blowers. In all other respects, theblowers of second set 70 may be similar to the centrifugal blowers 18 offirst set 60. In other embodiments, however, the blowers of second set70 may be structurally and functionally distinct from first set ofblowers 60, including reverse-curved centrifugal blowers, axial blowers,and other designs deemed suitable for the respective application.

In the embodiment illustrated in FIG. 5 b, plenum 115 may be arranged tointermediately direct cooling air flow to module inlet 116 along a flowdirection 109 that is substantially parallel to second direction vector50. It is also to be understood that the illustrations of FIGS. 1 b and5 b are schematic only, and merely represent the functional interactionof modules 10, 110, with an associated electronics chassis 12, 112.

The fan aerodynamic efficiency is critical to provide the required flowrate with relatively low power input. This is necessary to keep thedrive motor dimensions as compact as possible. Motor axial length shouldbe minimized to maintain the low overall height of the system andoptimum air entry condition for the downstream blower.

Table 1 represents actual performance measured on an example embodimentmodule arrangement as described in FIGS. 1 a and 1 b, compared to amodule arrangement as described in “prior art” FIGS. 3 a and 3 b.

TABLE 1 Example Delta from Embodiment Prior Art Example (FIG. 1) (FIG.3) Embodiment Air Power output 41 watts 41 watts — Tip Speed 2729 ft/min5739 ft/min +110%  Line Power input 195 watts 290 watts +49%    SoundPower 75 dBA 86 dBA +11 dBA

Table 2 represents actual performance measured on an example embodimentmodule design as described in FIGS. 1 a and 1 b, compared to a moduledesign as described in “prior art” FIGS. 4 a and 4 b. Note this data wasmeasured on a system that is approximately ten times larger than theTable 1 system with respect to heat load, demonstrating the scalingcapability of the technology.

TABLE 2 Example Delta from Embodiment Prior Art Example (FIG. 1) (FIG.4) Embodiment Air Power output 402 watts 402 watts — Tip Speed 5786ft/min 6597 ft/min +14% Line Power input 2175 watts 3500 watts +61%Sound Power NA NA NA

The invention has been described herein in considerable detail in orderto comply with the patent statutes, and to provide those skilled in theart with the information needed to apply the novel principles and toconstruct and use embodiments of the invention as required. However, itis to be understood that various modifications can be accomplishedwithout departing from the scope of the invention itself.

1. A cooling fan module for motivating air flow through an electronicschassis, said module comprising: an enclosure having an air inletthrough which the air flow is drawn from said electronics chassis; atleast two centrifugal blowers disposed within said enclosure and inparallel motivating the air flow along a first direction vector throughsaid air inlet, each of said centrifugal blowers comprising: (i) ascroll housing defining an air inlet and an air discharge; (ii) aforward-curved impeller having a diameter dimension, and defining anaxis of rotation, said axis extending through said housing air inlet andsubstantially parallel to said first direction vector; and (iii) a motorfor rotation of said impeller about said axis, wherein said respectiveaxes of rotation of said centrifugal blower impellers are in substantialaxial alignment with one another.
 2. A cooling fan module as in claim 1wherein said enclosure includes first and second ends separated by oneor more side walls, and said air inlet being disposed at said first end.3. A cooling fan module as in claim 1 wherein said centrifugal blowersare all disposed on a first side of a mid-plane of the electronicschassis.
 4. A cooling fan module as in claim 1 wherein said air inletsof each of said centrifugal blowers are arranged in said enclosure infacing relationship with said enclosure air inlet.
 5. A cooling fanmodule as in claim 1 wherein said motor of said centrifugal blowers isvariable speed.
 6. A cooling fan module as in claim 5 wherein said motorof each of said centrifugal blowers is independently controlled.
 7. Acooling fan module as in claim 1 wherein said air discharges of saidcentrifugal blowers are arranged to emit air along a second directionvector which is substantially perpendicular to said first directionvector.
 8. A cooling fan module as in claim 1 wherein said scrollhousing of each of said centrifugal blowers includes a single air inlet.9. A cooling fan module as in claim 1 wherein said scroll housing ofeach of said centrifugal blowers expands both radially and axially fromproximate to a cutoff to said air discharge.
 10. A cooling fan module asin claim 1 wherein said centrifugal blowers are axially spaced apartalong said axis by a first distance of about one half of said impellerdiameter dimension.
 11. A cooling fan module for pulling air flowthrough an electronics chassis, said module comprising: an enclosurehaving an air inlet through which the air flow is drawn from saidelectronics chassis; a first set of a plurality of centrifugal blowersdisposed within said enclosure and in parallel motivating the air flowalong a first direction vector into said enclosure, each of saidcentrifugal blowers of said first set comprising; (i) a scroll housingdefining an air inlet and an air discharge; (ii) a forward-curvedimpeller having a diameter dimension, and defining an axis of rotation,said axis extending through said housing air inlet and substantiallyparallel to said first direction vector; and (iii) a motor for rotationof said impeller about said axis, wherein said respective axes ofrotation of said centrifugal blower impellers are in substantial axialalignment with one another; a second set of one or more blowers disposedwithin said enclosure and motivating the air flow along a seconddirection vector into said enclosure, said second direction vector beingsubstantially perpendicular to said first direction vector.
 12. Acooling fan module as in claim 11 wherein said second set of one or moreblowers is disposed proximate to said enclosure air inlet.